The M60 machine gun is an excellent weapon but improvements are possible and desirable. In particular, there are certain areas where improvements are especially desirable.
The M60 machine gun has its feeding mechanism arranged in a pivoted cover which is raised to load a belt of cartridges into the gun and then closed to render the feeding mechanism operative. The feeding mechanism includes cam means operated by the reciprocating bolt assembly which must be in its rearward position for proper engagement of the cam follower carried by the assembly with the cam means of the feeding mechanism when the cover is moved to closed position. Thus, when the bolt assembly is in its forward position with the cover open, if the latter is closed the bolt assembly cannot be moved rearwardly to cock the gun and if it is forced rearwardly there is a possibility of the cam follower thereon actually damaging the feeding mechanism. Thus, the present construction presents a possibility not only of damage to the feeding mechanism but also of a dangerous battle situation because of undue delay in cocking the weapon because the gunner must open the cover before he can retract the bolt assembly to cock the gun and then must reclose the cover before he can fire.
As mentioned above, the M60 machine gun is gas-operated. On occasion, for various reasons, gas pressure is insufficient to move the bolt assembly to its full rearward position for cocking engagement with the sear of the trigger mechanism. Even though the bolt assembly is not moved to its full rearward position, however, gas pressure may be sufficient to move the assembly rearwardly a distance sufficient to cause the feeding mechanism to feed another cartridge into position to be transferred by the bolt assembly into the barrel chamber and subsequently fired. The foregoing situation results in a runaway gun, i.e., it will continue to fire even though the trigger is released; manifestly a dangerous situation.
On prolonged firing, the barrel of the M60 machine gun becomes quite hot and for continued use must be replaced by the usual spare. To enable rapid replacement without delay, heat-insulating protective hand coverings, such as asbestos mittens, now are employed for removal of a hot barrel. The use of such mittens not only is an expensive nuisance but also contributes to delay in barrel replacement.
The M60 machine gun also is provided with a bipod support assembly secured to the barrel. The assembly is not readily detachable and removable from the barrel. Consequently barrel spares normally are provided with such bipod support assemblies, thus necessitating the provision of more than one bipod support assembly for each gun.
The gas-operated piston and cylinder of the M60 machine gun also is somewhat bulky and inaccessible for cleaning. The cylinder is provided with a cleaning port aligned with the barrel gas port, with the cleaning port being closed by a threaded plug. The forward end of the cylinder is closed by an extension held in place by a clamp nut with a lock washer. Both the plug and the extension of the cylinder are retained against loss by lock wires because the usual threads and lock nuts fail under extreme heat conditions. Since lock wires cannot be replaced readily in the field, the gas system is cleaned only infrequently with resulting possible sluggish operation of the gun. Furthermore, the cleaning port plug sometimes is lost and the gun thereby rendered inoperative because of loss of adequate gas pressure.
The rearward end of the gas cylinder is provided with interior threads engaged by exterior threads on a nut to provide a forwardly facing shoulder engageable by the piston on its rearward travel. Both this nut and the cylinder extension unnecessarily complicate the construction of the cylinder and piston arrangement and add unnecessary weight to the weapon.
It also has been found that control of the gun is difficult when firing from a standing position.